With the opening of the Clyfford Still Museum last fall, a number of galleries have mounted shows highlighting abstraction as salutes to the fledgling institution. The CSM has given its blessing to some of these, while others have sprung up spontaneously. I've enjoyed seeing most of these shows, but it occurred to me that they haven't achieved a critical mass, which they could have. If you think about it, the CSM-sponsored community celebration could have been what the Biennial of the Americas should have been and wasn't — a cavalcade of interlocking art events on a unified theme. There weren't enough Still tributes to truly achieve this, however, and they have appeared over a swath of months instead of being compressed together on the calendar.

It was the powers-that-be at the CSM that created the latter problem by requesting that the celebratory shows be held until after New Year's Day so that the museum's November opening would stand alone. Some institutions, like the Denver Art Museum and the Kirkland Museum, tacitly refused to comply, and opened their shows before the CSM came on line. If every venue had done that, there would have been a world-class celebration of abstraction in Denver, setting the context for the unveiling of Still's stunning paintings. As it is, some of the best shows have simply blended in with the rest of the season. Oh, well. Since this was a once-in-a-lifetime opportunity, it won't be a problem in the future.

Putting my disappointments aside and turning to the spectacular multi-part exhibit at Robischon Gallery, AB-EX: Positions and Dispositions, I've got to admit that it's a festival of abstraction all by itself. The show, organized by gallery owners Jim Robischon and Jennifer Doran, comprises four nice solos and a small group outing.

The exhibit opens with a good-sized section dedicated to Gary Komarin, a neo-abstract expressionist, in the spaces that open off the entry. Komarin is a direct heir to the New York School tradition, as he was a protégé of Philip Guston, who first established his fame as an abstract expressionist before moving on to the disturbing but better-known cartoonish images he did at the end of his career.

Truth be told, though Komarin has embraced the active brushwork, the drips and runs, the predominating color fields — all of it applied in a frenzy of automatism — that are the hallmarks of abstract expressionism, he also incorporates decidedly un-abstract-expressionist elements, like the references to three-dimensional objects. In "Rue Madame in Red No. 3," a mixed-media work on canvas, a field made up of different shades of red is violated in the top third of the composition by clusters of drawn details like a linear cube and a vaguely cylindrical shape. It's impossible not to think of Guston's cartoons when looking at these elements, a reference that's also easy to see in the gorgeous "The Last Ride of General Sartoris" and a number of others.

In the small gallery in the back is an intimate group show made up of four works: two paintings by Jack Jefferson and one each by Frank Lobdell and Charles Strong. Though all three could be called followers of Still, Jefferson was the only one who studied personally with the abstract-expressionist master, back in the 1940s. The other two absorbed Still's influence by proxy: Lobdell later shared a studio with Jefferson, while Strong was a student of both at the San Francisco Art Institute. Strong, who was born in Colorado, also met with Still when he was an artist in residence at the University of Colorado at Boulder in 1960. The influence of Still is easy to see in the work of each — especially in the Lobdell — but each has made it his own.

Back through the Komarin rooms and into the spaces beyond, there's a major selection of Manuel Neri's work in the form of painted bronzes and works on paper; both take on his signature topic, the nude female figure. Neri is a Bay Area artist who emerged as a figural abstractionist — a kind of work that took hold in the late 1950s — and also embraced the funk aesthetic that flowered in San Francisco. In many ways, Neri's approach is distinct from abstract expressionism, particularly the fact that his work is not purely abstract, but rather abstracted. But his approach is definitely expressionist in the handling of the surfaces and in the juxtaposition of colors in the sculptures, and the same is true of the drafting and the colors in the drawings.

In a piece from his "Prietas" series, Neri has created a standing figure, her arms held out in front of her. Her torso, hands and face are rendered crudely and free of details. The surface of the piece is scabrous, covered with lumps and hollows. Neri has finished it by accenting the natural patina on the bronze with passages painted in yellow and white oil pigments. The drawings, also of women, are the perfect extension of the sculptures — or vice versa — in that they capture in two dimensions the insubstantiality of the works. In both, the margins of the forms have been softened, which lends them a kind of ethereal quality, as does the unnatural colors Neri uses.

To the right of the Neris is a tight exhibit featuring more than a dozen small pieces on paper by Denver's own Dale Chisman, who died in 2008. When he passed away, Chisman was generally considered to be among the finest artists to have ever worked in Colorado. He provided a link between the first generation of abstractionists in Colorado and the current crop. Although Chisman lived in New York for a time, earning some measure of fame, he returned to Colorado in the 1980s and became an arts advocate, helping to create MCA Denver in the 1990s.

At Robischon, Chisman is represented by paintings on paper that are both related to his better-known paintings on canvas and yet clearly different. Chisman allowed the medium to determine his approach, and in that way exploited properties that were unique to each. Although it is a more subtle distinction than Neri's segue from sculpture to drawing, Chisman's work on paper required a different set of skills than his works on canvas — and he was unquestionably adept at both. In these exquisitely detailed paper works, there's a delicacy of line and form that would be just about impossible to pull off in the brawnier arena of paint on canvas. Some are clearly preparatory painted sketches meant to be realized in painting. But most are spontaneous gestures run off quickly as Chisman apparently explored and experimented with form and line.

Another artist who was equally adept with canvas and paper was Robert Motherwell, a giant in the abstract-expressionist movement. As a result of this preeminence and the high quality of his signature work, AB-EX reaches its climax in the large back space, where more than a dozen Motherwell prints are on display. Before the opening of the Still Museum, Motherwell was the abstract expressionist best represented in Denver, with the Denver Art Museum having acquired an in-depth collection surveying his career (now on view on level 3 of the Hamilton in another salute to the opening of the CSM).

At Robischon, there are examples of the two poles of Motherwell's aesthetic, which he worked on simultaneously. There are the slashing strokes and bars associated with action painting and drawing, as in "Elegy Study I," and there are the ones anchored by straight — or mostly straight — lines, which represent his more minimal approach, as in "Untitled (Open)." Motherwell worked with a very simple vocabulary of forms, and his palette was typically reduced to just a few bold shades. In "Elegy Study I," which is part of Motherwell's most famous series of pieces, meant to commemorate the Spanish Republic just as Picasso's "Guernica" does, the artist has limited the palette to black and white applied to a sandpaper-colored ground. In "Untitled (Open)," it's just black and red standing out against the bright white of the blank paper.

I went to AB-EX at Robischon with a friend, who said to me that he thought it was the best show he'd ever seen in a commercial gallery. I wouldn't go that far, but I would say it's one of them.